This invention relates generally to the field of connectors, and more particularly to connectors which may coupled and uncoupled by hand or by pulling apart by application of a prescribed force. In one specific application, the invention relates to connectors which may be used to connect air lines and/or electrical signal and power lines for a rail car braking system.
Current braking systems used on most freight trains in the United States are based on a technology that was developed almost one hundred years ago. Such systems rely on the use of pressurized air to both control and power the brakes. In order to supply pressurized air to the rail cars, an air line is provided along each rail car. When the rail cars are connected, each air line is coupled together to form a single air line running the length of the train. The coupling mechanism generally employed to join each air line is commonly referred to as a "gladhand" coupling and has remained substantially unchanged over the last century.
Gladhand couplings are hermaphroditic, substantially identical, so that either end of a rail car can connect to either end of another rail car. To connect a pair of gladhand couplings, one abuts the couplings adjacent each other and rotates the couplings with their attached air hoses in opposite directions until fully engaged. To prevent the couplings from disconnecting when subjected to vibration, some have a locking device which prevents rotation of the couplings once they have been joined.
Although gladhand couplings have been generally successful in coupling air lines of conventional pneumatic braking systems, such systems have significant drawbacks which have prompted development of newer systems. More particularly, with pneumatic systems braking time is affected by the speed with which air pressure changes travel along the train. For trains having large numbers of rail cars, a significant delay may be experienced while the air travels the length of the train. As a result of this, trains require longer stopping distances and may be prematurely slowed to ensure a safe stop.
Recently, a new braking system has been proposed. The system is referred to a an Electrically-Controlled-Pneumatic (ECP) braking system. The ECP system relies on air to power the brakes, but controls actuation of the brakes electronically. The ECP system therefore requires both air and electrical connections between cars. When ECP systems become fully implemented, the electrical lines which control the brakes may also be used for other signals for controls and data throughout the train. This will logically lead to automatic coupling/decoupling of cars with electronic verification eliminating the necessity and hazard of persons working between rail cars.
Gladhand couplings have a features which make them undesirable for ECP braking systems and unsuitable for automatic coupling/decoupling. Most importantly, they must be rotated to make the air line connection. This rotating action is ill-suited to integrating an electrical connector into the coupling. Further, since rail cars couple/decouple in a push-pull direction, automatic coupling with a connector requiring rotation would be difficult or impossible. Gladhand couplings also require the air to negotiate a 90 degree angle as it passes through the coupling, unnecessarily reducing the efficiency of any ECP system.
One style of integrated air/electrical connectors suitable for use with the ECP system is described in co-pending U.S. application Ser. No. 08/548,993, filed Oct. 27, 1995, the complete disclosure of which is herein incorporated by reference. Although workable, these connectors require twisting of a coupling nut to complete their mating which would be less desirable than a simple push-pull mating, particularly for automatic coupling of rail cars. Also, given the environment in which these connectors must operate, it would be desirable to produce a connector which is less complicated and has fewer parts.
Hence, what is required is an integrated air/electrical connector system consisting of hermaphroditic connectors which mate/unmate either manually or automatically, with the automatic method requiring nothing more than a simple push-pull motion. Any latching method must be sufficiently rigid to avoid unintentional uncoupling while in use.